Refractory support for shell molds

ABSTRACT

This disclosure relates to devices for supporting molds while they are being poured to reduce distortion of the mold caused by the weight and movement of the molten metal-containing material during and after it is poured into the mold. Support elements made of ceramic or other heat resistant materials are shaped and positioned to support selected wall portions of the mold.

United States Patent 1 Carnot et al.

[ REFRACTORY SUPPORT FOR SHELL MOLDS [75] lnventors:John J. Carnot, West Orange, Stanley v Carroll Tingquist, Sparta, Ronald Robert Robb, Dover, Roy Chester Feagin, Mountain Lakes a11ofN.J.

[73] Assignee: Howmet Corporation. Muskegon.

Mich.

[22] Filed: Aug. 10, 1971 [21] App1.No.: 170,645 7 Related US. Application Data [63] Continuation of Ser. No. 808,614, March 19, 1969,

abandoned.

[52] U.S.Cl ..164/361 [51] lnt.Cl ..l ..B22c 9/02 [58] Field of Search ..164/21, 43-, 333,

[451 Apr. 24, 1973 Adams [5 7] ABSTRACT This disclosure relates to devices for supporting molds while they are being poured to reduce distortion of the mold caused by the weight and movement of the molten metal-containing material during and after it is poured into the mold. Support elements made of ceramic or other heat resistant materials are shaped and positioned to support selected wall portions of the mold.

4 Claims, 5 Drawing Figures REFRACTORY SUPPORT FOR SHELL MOLDS CROSS REFERENCE TO RELATED APPLICATION This is a continuation of my application Ser. No. 808,6l4, filed Mar. 19, I969 abandoned.

BACKGROUND OF THE INVENTION In the production of casting made from metal-containing materials certain refractory shell molds are used which do not havesufficient strength and rigidity to resist the forces and pressures to which they are subjected during the pouring operation. Shell molds vary in size and shape depending on the object being molded and each shell mold has different support requirements depending on the wall structure of the mold and the type of pouring operation used. Pouring operations vary as to the rate of pouring of the charge and movement or flow of the charge after its entrance into the mold. Small molds generally have sufficient strength to receive the metal-containing material without significant expansion or other distortion; however, in the use of larger molds the maintenance of dimensional integrity during the pouring operation is a significant problem and heretofore no satisfactory solution has been found.

Expansion or distortion of a mold during the pouring operation often requires rejection or scraping of the casting or the expense of machining the casting to obtain the desired dimensions.

SUMMARY OF THE INVENTION The present invention provides a prefabricated prefired support element to support a wall area of the mold which is readily installed and held in its desired position to prevent mold distortion.

Broadly, the present invention comprises a refractory shell mold arrangement including at least one support element fabricated from a heat resistant material having thermal expansion characteristics compatible with the mold to'be supported in which the element has a surface area conforming with and positioned to the support wall area of the mold and includes structural means for resisting movement of said surface area during the pouring operation.

It is a feature of the invention that the support ele ments are prefired prefabricated elements designed for ready use with molds of particular wall configuration.

It is also a feature of the invention that prefired ceramic support elements suitably shaped and positioned may retain the desired configuration of the mold 'during pouring to maintain the casting dimensions within allowed tolerances.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawing,

FIG. I is a sectional elevational view of a turbine wheel mold supported in accordance with the invention.

FIG. 2 is a plan view of another supported mold which is generally cylindrically in shape;

FIG. 3 is a sectional view taken along line 3--3 of FIG. 2; I

FIG. 4 is a sectional elevational view of an other supported mold; and

FIG. 5 is a plan view of a support clip.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIGS. 1 and 5 of the drawings, turbine wheel 1 includes hub sections 2, blading section 3 and riser 4. Support clips 6 have upper arms 7 and lower arms 8. Arms 7 and 8 are integrally connected by elbow sections 5. If desired the arms and elbow sections may be separate elements suitably connected. Arms 7 and 8 are molded of ceramic material and preferably six to 10 clips would be spaced around the blading section 3 of the wheel to provide support to various areas of the blading section. Arms 7 and 8 are disposed such that their centerlines intersect to form less than a 45 angle.

Clips 6 are preferably shaped to engage the surface of the blading section at wall contact areas 9. Cross pieces 1 1 are also used to facilitate obtaining a plurality of support points along area 9. Structural means such as cross pieces 11 may be secured to clips 6 using refractory material to prevent relative movement between these elements as the blading section expands and moves during the pouring operation. If the mold is to be handled after assembly of the clips and cross pieces and prior to the pouring operation, the clips may be conveniently held in place using twine or rope.

Turning to FIGS. 2 and 3, mold 13 has outer wall 14, inner wall 16 and riser 17. The outer and inner walls are integrally joined together by upper surface wall 18. The mold is supported by interior brace 19 to reduce movement of the inner wall 16 inwardly through exerting resistance against areas of the wall and ceramic ring support 21 similarly reduces movement of outer wall 14. Ring 21 may be placed at any suitable height along wall 14 and more than one ring may be used.

Referring to FIG. 4, mold 22 with riser 23 has upper wall 24, lower wall 26 and side wall 27. Lower wall 26 is supported by support element 28 which is shaped to conform with the lower wall to provide contiguous support.

Cross pieces 11 or other spacer elements may be used to fill the space between a support element and a mold wall, thereby increasing the number or size of the support areas.

The clips and other support elements are fabricated of heat resistant material which has rates of expansion characteristics of the mold to be supported so that as the mold expands or contracts the support element will expand or contract sufficiently to prevent distortion of the mold by the support elements. The expansion characteristics of the support elements are therefore compatible with the expansion characteristics of the molds they are intended to support.

We claim:

1. A refractory shell mold support apparatus for supporting wall areas of a shell mold during the pouring operation comprising a plurality of support elements each having an inner surface shaped and readily positionable to support the mold at more than one wall area of the shell, said elements in turn comprised of heat resistant non-metallic refractory material having thermal expansion characteristics compatible with the expansion characteristics of the refractory shell mold so that as the mold expands or contracts the support element will correspondingly expand or contract sufficiently to prevent distortion of the mold,-the inner surface area on the element substantially conforming with and positioned to the support wall area of the mold, and structural means spaced between the mold wall and the element for resisting movement of said surface of the element during said pouring operation.

2. The apparatus of claim 1 in which the support element is adapted to be positioned within the mold to resist inward movement of a mold wall.

3. A refractory shell mold apparatus for supporting wall areas ofa shell mold comprising a plurality of support elements shaped and readily positionable to support portions of mold wall areas subjected to forces during pouring of the mold, each element in turn,

l. formed of a heat resistant material having a thermal expansion characteristics compatible with the thermal expansion characteristics of the refractory shell mold, and including 2. two legs and an elbow section which legs are connected through said elbow section in such a manner that the angle between the centerlines of the legs is less than 45 degrees and in which each leg has a surface area which conforms to the mold shape to supportingly engage a mold wall area.

4. The apparatus of claim 3 in which the support elements support other wall areas through spacer elements positioned between the support element and the mold wall. 

1. A refractory shell mold support apparatus for supporting wall areas of a shell mold during the pouring operation comprising a plurality of support elements each having an inner surface shaped and readily positionable to support the mold at more than one wall area of the shell, said elements in turn comprised of heat resistant non-metallic refractory material having thermal expansion characteristics compatible with the expansion characteristics of the refractory shell mold so that as the mold expands or contracts the support element will correspondingly expand or contract sufficiently to prevent distortion of the mold, the inner surface area on the element substantially conforming with and positioned to the support wall area of the mold, and structural means spaced between the mold wall and the element for resisting movement of said surface of the element during said pouring operation.
 2. The apparatus of claim 1 in which the support element is adapted to be positioned within the mold to resist inward movement of a mold wall.
 2. two legs and an elbow section which legs are connected through said elbow section in such a manner that the angle between the centerlines of the legs is less than 45* degrees and in which each leg has a surface area which conforms to the mold shape to supportingly engage a mold wall area.
 3. A refractory shell mold apparatus for supporting wall areas of a shell mold comprising a plurality of support elements shaped and readily positionable to support portions of mold wall areas subjected to forces during pouring of the Mold, each element in turn,
 4. The apparatus of claim 3 in which the support elements support other wall areas through spacer elements positioned between the support element and the mold wall. 